Oestrogens and breast cancer: biological considerations

The biology of oestrogens as applied to the development and progression of breast cancer has been reviewed. Particular consideration has been given to: (i) the sources by which the breast and its tumours may be supplied with oestrogen; (ii) the patterns of endogenous oestrogens within the breast; (iii) the mechanisms by which oestrogens may exert their action; and (iv) the molecular events which follow oestrogen deprivation and which may lead to hormone independence. From a greater understanding of these fundamental processes, novel antioestrogenic measures are being developed which represent more acceptable endocrine treatments for patients with breast cancer and offer the hope of preventative medicine for individuals at high risk of the disease.